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Veterinary ophthalmology2023; 27(3); 277-285; doi: 10.1111/vop.13171

Macrodendritic ulcerative keratitis and conjunctival lymphoid hyperplasia in horses with equine herpesvirus-2 and equine herpesvirus-5 infections.

Abstract: The aim of this study was to describe the clinical, confocal microscopic, histologic, and virologic features of horses with macrodendritic ulcerative keratitis and conjunctival lymphoid hyperplasia associated with equine herpesvirus-2 and equine herpesvirus-5 infection. Methods: Four foals with bilateral ocular disease. Methods: Complete ophthalmic examination was performed for each horse, and corneal samples were collected for cytology and microbiologic evaluation, including virus isolation and molecular diagnostics for the equine herpesviruses. In vivo confocal microscopy examination of the cornea was performed in two horses. Conjunctival biopsies for histopathology were collected from two horses with nodular conjunctival thickening. Results: Each horse had bilateral, large, superficial dendritic corneal ulcerations that covered extensive regions of the corneal surface. Corneal in vivo confocal microscopy examination in two horses detected inflammatory cells and populations of morphologically abnormal corneal epithelial cells adjacent to the ulcerations. The abnormal epithelial cells included round, relatively small, hyperreflective cells intermixed with elongated, enlarged, hyperreflective cells. Equine herpesvirus-2 was isolated from corneal samples of 2 horses and detected by PCR assay in the other two horses. Equine herpesvirus-5 was also detected by PCR assay in three of the horses. Conjunctival histopathology identified predominantly lymphocytic infiltrates. The macrodendrites and conjunctival masses resolved with topical antiviral therapy (cidofovir or idoxuridine) in all horses and did not recur. Conclusions: The equine gammaherpesviruses may be associated with the development of macrodendritic ulcerative keratitis and conjunctival lymphocytic masses in foals. In vivo confocal microscopy of horses with macrodendrites revealed similar findings to other host species with herpetic dendritic keratitis.
© 2023 The Authors. Veterinary Ophthalmology published by Wiley Periodicals LLC on behalf of American College of Veterinary Ophthalmologists.
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Publication Date: 2023-12-05 PubMed ID: 38053223DOI: 10.1111/vop.13171Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research study investigates the correlation between equine herpesvirus-2 and equine herpesvirus-5 infections and certain horse eye conditions, specifically macrodendritic ulcerative keratitis and conjunctival lymphoid hyperplasia.

Methodology and Experiment

The experiment was carried out on four young horses (foals) with both-sided eye disease. The team performed several procedures:

  • A complete ophthalmic examination was done on each horse
  • Corneal samples were collected for cytological and microbial assessments
  • Viral isolation and molecular diagnostics were conducted for equine herpesviruses
  • In vivo confocal microscopy of the cornea was performed on a pair of horses
  • Conjunctival biopsies were collected from two horses with nodular conjunctival swelling

Results and Findings

Upon examination, each horse was found to suffer from large, superficial dendritic corneal ulcerations that covered extensive areas of the cornea. The examination via confocal microscopy uncovered visibly abnormal corneal epithelial cells near the ulceration and significant inflammatory cells presence.

  • The abnormal cells were characterized by round, small, hyperreflective cells mixed with elongated, larger, hyperreflective cells.
  • Equine herpesvirus-2 was isolated from the corneal samples of two horses and detected by Polymerase Chain Reaction (PCR) assay in the other two.
  • Three of the horses were also founded to have equine herpesvirus-5 when tested using PCR assays.
  • Conjunctival histopathology unveiled predominantly lymphocytic infiltrates.

Conclusion and Treatment

The results indicate a possible link between equine gammaherpesviruses and the development of macrodendritic ulcerative keratitis and conjunctival lymphocyte masses in foals. Conjunctival growths and macrodendrites were successfully treated with topical antiviral therapy (cidofovir or idoxuridine), and there were no recurrences. The use of in vivo confocal microscopy on horses with macrodendrites showed similar results to other host species with herpetic dendritic keratitis.

Cite This Article

APA
Ledbetter EC, Cutler TJ, Irby NL. (2023). Macrodendritic ulcerative keratitis and conjunctival lymphoid hyperplasia in horses with equine herpesvirus-2 and equine herpesvirus-5 infections. Vet Ophthalmol, 27(3), 277-285. https://doi.org/10.1111/vop.13171

Publication

Veterinary ophthalmology
ISSN: 1463-5224
NlmUniqueID: 100887377
Country: England
Language: English
Volume: 27
Issue: 3
Pages: 277-285

Researcher Affiliations

Ledbetter, Eric C
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Cutler, Timothy J
  • Palm Beach Veterinary Specialists, West Palm Beach, Florida, USA.
Irby, Nita L
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.

MeSH Terms

  • Animals
  • Horses
  • Horse Diseases / pathology
  • Horse Diseases / virology
  • Herpesviridae Infections / veterinary
  • Herpesviridae Infections / pathology
  • Herpesviridae Infections / virology
  • Female
  • Male
  • Varicellovirus / isolation & purification
  • Eye Infections, Viral / veterinary
  • Eye Infections, Viral / pathology
  • Eye Infections, Viral / virology
  • Keratitis, Dendritic / veterinary
  • Keratitis, Dendritic / pathology
  • Keratitis, Dendritic / drug therapy
  • Corneal Ulcer / veterinary
  • Corneal Ulcer / pathology
  • Corneal Ulcer / virology
  • Rhadinovirus / isolation & purification
  • Conjunctival Diseases / veterinary
  • Conjunctival Diseases / pathology
  • Conjunctival Diseases / virology

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